Multi-electrode platform for selective electrochemical sensing: 3D-printed insulating plastic is turned into a five-electrodes chip.

We report a method to turn a 3D-printed plastic piece into a five-electrodes chip for multiple analytes detection. A chip containing Pd, Ni, and Ru working electrodes is used to sense hydroquinone, acetaminophen, salicylic acid, and hydroxychloroquine at once. The analysis is sequentially achieved simply by changing the proper electrode connection, without changing mobile parts, neither adding reactants, nor electrolytes. This strategy is an alternative for low-cost selective electrochemical detection.

Glycerol Is Converted into Energy and Carbonyl Compounds in a 3D-Printed Microfluidic Fuel Cell: In Situ and In Operando Bi-Modified Pt Anodes.

The combination of energy and chemical conversion can be achieved by designing glycerol fuel cells. However, the anode must promote the reaction at onset potentials low enough to allow a spontaneous reaction, when coupled to the cathodic reaction, and must be selective. Here, we build a three-dimensional (3D)-printed glycerol microfluidic fuel cell that produces power concomitantly to glycolate and formate at zero bias. The balance between energy and the two carbonyl compounds is tuned by decorating the Pt/C/CP anode in situ (before feeding the cell reactants) or in operando (while feeding the cell with reactants) with Bi. The Bi-modified anodes improve glycerol conversion and output power while decreasing the formation of the carbonyl compounds. The in operando method builds dendrites of rodlike Bi oxides that are inactive for the anodic reaction and cover active sites. The in situ strategy promotes homogeneous Bi decoration, decreasing activation losses, increasing the open-circuit voltage to 1.0 V, and augmenting maximum power density 6.5 times and the glycerol conversion to 72% at 25 °C while producing 0.2 mmoL L-1 of glycolate and formate (each) at 100 µL min-1. Such a performance is attributed to the low CO poisoning of the anode, which leads the glycerol electrooxidation toward a more complete reaction, harvesting more electrons at the device. Printing the microfluidic fuel cell takes 23 min and costs ∼US$1.85 and can be used for other coupled reactions since the methods of modification presented here are applied to any existing and assembled systems.

Harvesting Energy from an Organic Pollutant Model Using a New 3D-Printed Microfluidic Photo Fuel Cell.

The combination of a fuel cell and photocatalysis in the same device, called a photo fuel cell, is the next generation of energy converters. These systems aim to convert organic pollutants and oxidants into energy using solar energy as the driving force. However, they are mostly designed in conventional stationary batch systems, generating low power besides being barely applicable. In this context, membraneless microfluidics allows the use of flow, porous electrodes, and mixed media, improving reactant utilization and output power accordingly. Here, we report an unprecedented reusable three-dimensional (3D) printed microfluidic photo fuel cell (µpFC) assembled with low-content PtOx/Pt dispersed on a BiVO4 photoanode and a Pt/C dark cathode, both immobilized on carbon paper. We use fused deposition modeling for additive manufacturing a US$ 2.5 µpFC with a polylactic acid filament. The system shows stable colaminar flow and a short time light distance. As a proof-of-concept, we used the pollutant-model rhodamine B as fuel, and O2 in an acidic medium at the cathode side. The mixed-media 3D printed µpFC with porous electrodes produces remarkable 0.48 mW cm-2 and 4.09 mA cm-2 as maximum power and current densities, respectively. The system operates continuously for more than 5 h and converts 73.6% rhodamine by photoelectrochemical processes. The 3D printed µpFC developed here shows promising potential for pollutant mitigation concomitantly to power generation, besides being a potential platform of tests for new (photo)electrocatalysts.

3D-Printed glycerol microfluidic fuel cell.

A 3D-printed microfluidic fuel cell is presented. Fused deposition modeling is used to build a microchannel with a 0.015 cm2 cross-sectional area for stable colaminar flow conditions. A new 3D-Printed cell fed by glycerol displays a power density of 175 mW cm-2 at 0.9 V and 1.8 V of open-circuit voltage.

Insulating 3D-printed templates are turned into metallic electrodes: application as electrodes for glycerol electrooxidation.

We turned printed plastic pieces into a conductive material by electrochemical polymerization of aniline on the plastic surface assisted by graphite. The conductive piece was then turned into a metallic electrode by potentiodynamic electrodeposition. As a proof-of-concept, we built indirect-3D-printed Pd, Pt and Au electrodes, which were used for glycerol electrooxidation.